There has been proposed an air-conditioning apparatus equipped with a cross-flow fan configured so that the curved lines of an impeller form two circular arcs with different radii, in which the airflow of air passing between blades follows the blade surface more than in a single circular arc (see, for example, Patent Literature 1). In the technique described in Patent Literature 1, a curved line radius R2 of the impeller on the impeller outer circumferential side is larger than a curved line radius R1 of the impeller on the impeller inner circumferential side, so that “the blade thickness is approximately equal across the distance from the impeller inner circumferential side to the outer circumferential side”, or so that “the blade thickness takes a maximum at the impeller inner circumferential end, and is smaller in areas of the blade closer to the outer circumferential side”.
There has also been proposed an air-conditioning apparatus equipped with a cross-flow fan having blades with “a thickness distribution which takes a maximum thickness value on the impeller inner circumferential side of a blade, and is smaller in thickness value in areas of the blade closer to the outer circumferential side of the impeller of the blade”, in which the position of the maximum bend height of the blade is specified (see, for example, Patent Literature 2). The technique described in Patent Literature 2 improves the air volume performance for the same noise level by equipping a cross-flow fan with such blades.
There has moreover been proposed an air-conditioning apparatus equipped with a cross-flow fan in which “the blade thickness is smaller in areas of the blade closer to the impeller outer circumferential side so that the inter-blade dimensions between individual blades become approximately equal on the outer circumferential side and inner circumferential side of the impeller” (see, for example, Patent Literature 3).
Again, there has been proposed an air-conditioning apparatus equipped with a cross-flow fan formed so that the thickness of a blade takes a maximum at a position 4% from the inner side of the chord of the blade, and is smaller in areas of the blade farther from the maximum thickness position of the blade and closer to the two ends of the blade (see, for example, Patent Literature 4).
There has been proposed a cross-flow fan in which the length of a blade is divided into a plurality of areas, and when the portion adjacent to a support plate is defined as a first area, the central portion of a blade is defined as a second area, and the portion between the first area and the second area is defined as a third area, the blade outlet angle on the blade outer circumferential edge is largest in the third area, is second largest in the first area, and is smallest in the second area (see, for example, Patent Literature 5).